Compliant cutoff saw assembly

ABSTRACT

A cutoff saw assembly incorporates a robot assembly with a compliant cutting apparatus to remove various undesired metal extensions from a casting. The assembly cooperatively and conjunctively controls the position of the casting using the robot assembly and the force exerted by the cutting apparatus on the casting using a compliance control system. The compliance control system includes a compliance actuator that is connected to a compliance regulator. Both the robot assembly and the compliance control system are connected to a system controller. The compliance actuator is connected to the cutoff blade to actively vary the force of the cutting blade with respect to the casting. The compliance regulator, which is connected to the system controller, will measure and regulate the pressure in the compliance actuator, such that the robot assembly and compliance control system can apply the required force to cut the casting.

FIELD OF THE INVENTION

[0001] The present invention relates generally to the field of metalcasting. More particularly the present invention relates to the cutoffof excess material on metal castings after it has been removed from themold. In even greater particularity the present invention relates to theremoval of riser or gate remnants after a cast part has been removedfrom the mold and to a process for perfecting the cutoff operation byconjunctively using a robot and a compliant cutoff saw.

BACKGROUND OF THE INVENTION

[0002] In the casting arts, molten metal is poured into a mold throughan opening in the top of the mold with a certain excess metal fillingthe channel to the mold cavity. When multiple parts are cast in the samecasting vessel, the mold will include channels in the form of a sprue toeach cavity for each part, which will create undesired dross on theouter surface of the casting once the molten metal has hardened into thecasting. The excess metal, such as those referred to as risers or gates,is frequently required to be removed by a cutoff or grinding operationin order for the casting to perform the purpose intended.

[0003] There are several common practices used by foundries to removethe risers or gates from the castings. These practices include, but arenot limited to, removal of the riser by means of a gas torch, a grinder,a conventional cutting blade or saw, or some similar machine forforcefully removing the dross. Moreover, after the gates or risers havebeen removed from the casting through any of these methods, the operatorcommonly has to further grind or finish the casting due to an uneven cutcaused by the respective trimming method.

[0004] The most common practice of cutoff operation is conventionallydone either by an operator controlling a machine having a cutoff bladeor automatically by means of a robotic device having a cutting blade. Inthe first example, the operator controls the machine that applies acutting force that may come from an external force, such as a hydrauliccylinder, or it may be generated manually by the operator physicallycontrolling the cutting force with his own strength and weight. In thesecond embodiment, the robot may be used to hold the casting to engage afixed cutoff saw, or to the contrary the robot may hold the cutoff sawwhile the casting is in a fixed position.

[0005] Robots have been used for years to control the movement of acasting through a cutoff blade. In addition, hydraulic, pneumatic orelectric cutoff saws have also been used in the common foundry to pushthe blade (or casting) through the casting (or blade). However, thesesolutions incorporating the use of the robot experience inherentproblems. For example, one inherent problem with the use of the robot tocontrol the cutoff operation is that the cutting wheel will have a shortabrasive life. In addition, this solution requires a long robot cycletime to cut the riser. Moreover, significant heat is generated in thecasting in such a method due to incorrect cutting force or pressure.Cutting forces that are lower than that prescribed by the blademanufacturer can cause excessive heat in the blade and the materialbeing cut. These high temperatures in the material can degrade theproperties of the material, resulting in scrap or wasted castings.Finally, there is frequently an inconsistent cut in the casting due todeflection and vibration in the robot, which could lead to possibledamage to both the robot and the cutoff saw due to inconsistent gates orrisers.

[0006] What is desired, then, and not found in the prior art, is acompliant cutoff saw assembly having a design that will accurately andefficiently cut a casting supported by a constant force or pressure aschosen for the particular casting to maintain the integrity of thecasting and the functionality of the assembly.

SUMMARY OF THE INVENTION

[0007] An object of the present invention is to provide an assembly forremoving excess material from a casting.

[0008] A further object of the present invention is to provide anassembly incorporating a compliant cutoff saw in conjunction with arobot to eliminate risers on castings.

[0009] Another object of the present invention is to provide an assemblyfor cutting through a casting that provides a cooler temperature in thecasting when being cut.

[0010] Yet a further object of the present invention is to provide anassembly for cutting through a casting that provides a consistent cut.

[0011] A further object of the present invention is to provide anassembly for cutting through a casting that has a long abrasive wheellife for the cutting element.

[0012] Another object of the present invention is to provide an assemblyfor cutting through a casting that will reduce deflection and vibrationin the robot by maintaining a constant cutting force.

[0013] In particular, the compliant cutoff saw assembly includes a robotassembly that is used with a cutting apparatus to remove variousundesired metal extensions from a casting. The compliant cutoff sawassembly has the ability to cooperatively and conjunctively control boththe position of the casting as well as the force exerted by the cuttingapparatus on the casting. The combination of controls allows thecompliant cutoff saw assembly to provide a clean and even incision onthe casting, which eliminates or at least reduces the amount of workrequired to finish the casting after the undesired metal extensions havebeen removed.

[0014] The robot assembly of the present invention includes amulti-positional robot arm that is connected to a system controller. Atooling clamp is connected to the free end of the robot arm, with thetooling clamp being used to engage and securely hold the casting to becut. The robot arm is able to move in three dimensions, and cantherefore position the casting in any dimension as desired by theoperator. Consequently, the cutting apparatus saw will be able to cutmost any side, surface or portion of the casting as desired by theoperator of the system.

[0015] The cutting apparatus of the present invention includes a framehaving a mounting assembly to which a support beam is pivotally affixed.A drive motor is preferably attached to the lower end of the supportbeam, with a cutoff blade being rotatably attached to the upper end. Thedrive motor is mechanically connected to the cutoff blade to drive andcontrol the rotation of the cutoff blade as desired by the operatorpursuant to the casting being cut.

[0016] In addition, the cutting apparatus includes a compliance controlsystem that includes a compliance actuator that is connected to acompliance regulator. The compliance actuator is connected between theupper end of the support beam and the frame, such that the complianceactuator will be able to actively vary the force of the cutting bladewith respect to the casting. The compliance regulator, which isconnected to the system controller, will measure and regulate thepressure in the compliance actuator. Consequently, the system controllerhas the ability to adjust the setpoint of the compliance regulator andprecisely control the movement of the robot arm so that the casting willbe cut as desired by the operator.

[0017] These and other objects and advantages of the invention willbecome apparent from the following detailed description of the preferredembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWING

[0018] A compliant cutoff saw assembly embodying the features of thepresent invention is depicted in the accompanying drawing which form aportion of this disclosure and wherein:

[0019]FIG. 1 is a side elevational view of the present invention of acompliant cutoff saw assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] Looking now to FIG. 1, the present invention of a compliantcutoff saw assembly 10 is illustrated. The compliant cutoff saw assembly10 encompasses a robot assembly 12 used in conjunction with a cuttingapparatus 20 to remove undesired metal extensions from a casting 16. Thecompliant cutoff saw assembly 10 has the ability to cooperatively andcontemporaneously control both the position of the casting 16 as well asthe compliance force exerted by the cutting apparatus 20 on the casting16 during the incision. The combination of these controls allows thecompliant cutoff saw assembly 10 to provide a clean and even cut intothe casting 16, which reduces or eliminates the amount of work requiredto finish the casting 16 once the metal extensions have been removed.

[0021] Referring to FIG. 1, the first component of the present inventionis the robot assembly 12 which includes a multi-positional robot arm 14that is connected to a system controller 18. A tooling clamp 15 isconnected to the unattached end of the robot arm 14, with the toolingclamp 15 being used to engage and securely hold the casting 16 to becut. The robot arm 14 is able to move in three dimensions, and cantherefore position the casting 16 in any dimension as desired by theoperator. Consequently, the compliant cutoff saw 20 will be able to cutany side, surface or portion of the casting 16 as desired by theoperator of the compliant cutoff saw assembly 10.

[0022] The second component of the present invention is the cuttingapparatus 20 which preferably includes a frame 22 that is sturdilypositioned on a ground or floor surface. The frame 22 comprises amounting assembly 24 that preferably includes a shaft and a pair ofbearings, with a support beam 26 being pivotally affixed to the mountingassembly 24. The support beam 26 includes a lower end 28 a and an upperend 28 b, with a drive motor 30 being attached to the lower end 28 a anda cutoff blade 32, such as an abrasive blade, carbide blade,diamond-tipped blade or other cutting device, being rotatably attachedto the upper end 28 b in the preferred embodiment. The drive motor 30 ismechanically connected to the cutoff blade 32 to drive and control therotation of the cutoff blade 32 as desired by the operator pursuant tothe requirements of the casting 16 being cut. Moreover, the drive motor30 is connected to a drive system 40, which preferably includes a vectordrive, such that the drive system 40 can control and vary the operationof the drive motor 30 and thus the speed of rotation of the cutoff blade16. The drive system 40 is further connected to said system controller18 via drive cable 42, such that the drive system 40 can receivecommunications from the system controller 18 directing operation of thedrive motor 30.

[0023] Most importantly, the cutting apparatus 20 of the presentinvention includes a compliance control system 31 that includes acompliance actuator 34 that is connected to a compliance regulator 36.In the preferred embodiment, the compliance actuator 34 is a pneumaticcylinder, although it is to be expected that any other actuator design,such as a hydraulic cylinder or electric actuator, could be incorporatedand effectively used in the present invention. Additionally, thecompliance regulator 36 is a conventional pressure regulator that iscommonly known in the art. The compliance regulator 36 is able tomeasure and control the pressure in the compliance actuator 34 andverify that compliance actuator 34 has the desired pressure setpoint asdetermined by the system controller 18 for the casting 16 to be cut withthe robot assembly 12.

[0024] As stated above, the cutting compliance actuator 34 is designedto support the cutting blade 32 with the force required depending on thephysical characteristics of the casting 16. Such support can come invarious ways that are not discussed in detail herein. However, in thepreferred embodiment of the present invention, the compliance actuator34 is positioned between the upper end 28 b of the support beam 26 andthe frame 22, such that the compliance actuator 34 will apply a givenforce to the upper end 28 b of the support beam 26 to pivot the supportbeam 26 about the mounting assembly 24. The pivoting motion of thesupport beam 26 will move the cutoff blade 32 toward and away from thecasting 16. The compliance force of the compliance actuator 34 iscontrolled by the compliance regulator 36. The compliance regulator 36is thereby further connected to the system controller 18 via a standardconnecting line 38 such that the system controller 18 is able to providea setpoint to the compliance regulator 36. The system controller 18 canthereby send a signal to the compliance regulator 36 to alter thepressure applied by the compliance actuator 34 as necessary pursuant tovarious factors, such as the shape of the casting 16, the composition ofthe material used in the casting 16, and the product standards of thecutoff blade 32 set forth by the blade manufacturer.

[0025] The steps of operation of the preferred embodiment of thecompliant cutoff saw assembly 10 are as follows. Initially, the systemcontroller 18 is programmed according to the physical characteristics ofthe casting 16 to be processed, and will direct the robot arm 14 toengage a newly-formed casting 16 with the tooling clamp 15. The systemcontroller 18 will then reposition the robot arm 14 and tooling clamp 15according to the program such that the casting 16 is proximate thecutting apparatus 20. More particularly, the casting 16 will bepositioned within the range of the cutoff blade 32. As stated above, themovement of the cutoff blade 32 will be in a general direction towardthe robot arm 14 and the casting 16. In particular, the compliant cutoffsaw assembly 10 will allow the cutoff blade 32 to move in the directionof the desired cut in the casting 16.

[0026] As discussed above, the system controller 18 is connected to therobot assembly 12, the compliance actuator 34, and the drive system 40of the cutting apparatus 20. Consequently, the system controller 18 isable to not only send a signal to the robot arm 14 and the complianceregulator 36, but it is also able to communicate with the drive system40 corresponding to the desired speed of rotation of the cutoff blade16. In particular, the system controller 18 is programmed to control therobot 12 and the cutting apparatus 20 pursuant to the requirements ofthe casting 16 being trimmed. The program for the system controller 18also establishes the necessary cutoff speed of the cutoff blade 32 andthe force for a particular casting 16 to be cut, and in turn the systemcontroller 18 sends a command to the compliance regulator 36 and/or thedrive system 40 for cutoff saw speed control.

[0027] The operation of the cutoff blade 32 of the present invention maybe either at a variable speed with the use of the drive system 40 or ata fixed speed. While speed control is not necessary in the presentinvention, it can improve the results of the trimming of the casting 16.For example, it is commonly known that the surface feet per minute(“SFPM”) of the cutoff blade 16 (revolutions per minute times thecircumference of the cutting blade 16), decreases as the cutoff blade 16gets smaller. As the SFPM decreases, the cutoff blade 16 is lessefficient and will cut less aggressively. This provides negativeresults, in that not all of the horsepower of the motor 30 is used, heatis generated in the casting 16, and cut-off times of the compliantcutoff saw assembly 10 are longer. Consequently, keeping the SFPM at aconstant reduces these associated problems that waste time and castings.

[0028] In addition, a wheel measurement device (not illustrated) may beconnected to the cutting apparatus 20 to monitor and adjust the speed ofthe cutoff blade 32 relative to the diameter of the cutoff blade 32. Bymonitoring the speed of the cutoff blade 32, the system controller 18 isable to maintain a constant surface speed of the cutoff blade 32.

[0029] It should further be noted that while the preferred embodimentdescribed above teaches the use of the robot 12 holding the casting 16,additional embodiments may reverse the positioning of the casting 16 andthe cutoff blade 32. That is, a further embodiment of the presentinvention may require that the casting 16 be held by the support beam 26or the frame 22, while the cutoff blade 32 rotatably mounted to the freeend of the robot arm 14. Such a design would nonetheless include acompliance control system 31 similar to the one described above so thatthe operator would be able to trim the casting 16 as desired.

[0030] Thus, although there have been described particular embodimentsof the present invention of a new and useful COMPLIANT CUTOFF SAWASSEMBLY, it is not intended that such references be construed aslimitations upon the scope of this invention except as set forth in thefollowing claims.

What is claimed is:
 1. A cutoff saw assembly for removing excessmaterial from a casting, said assembly comprising: a robot arm to holdthe casting; a system controller connected to said robot arm to controlmovement of said robot arm; and a cutoff apparatus connected to saidsystem controller, said cutoff apparatus including a compliant cutoffsaw; wherein said system controller cooperatively positions said robotarm with the casting proximately with said cutoff saw and determines thecompliance of said cutoff saw.
 2. The cutoff saw assembly as describedin claim 1 wherein said cutoff apparatus further comprises a compliancecontrol system connected to said frame.
 3. The cutoff saw assembly asdescribed in claim 2 wherein said compliance control system comprises anactuator controlling the force of said cutoff saw, said actuator furthercontrolling the compliance of cutoff saw when engaged by the casting. 4.The cutoff saw assembly as described in claim 3 wherein said actuator isa hydraulic actuator.
 5. The cutoff saw assembly as described in claim 3wherein said actuator is a pneumatic actuator.
 6. The cutoff sawassembly as described in claim 3 wherein said actuator is an electricactuator.
 7. The cutoff saw assembly as described in claim 3 whereinsaid compliance control system further comprises a compliance regulatorconnected between said actuator and said system controller to controlthe operation of the actuator.
 8. The cutoff saw assembly as describedin claim 2 wherein said cutoff apparatus comprises: a frame having amounting assembly; a support beam pivotally affixed to said mountingassembly, said support beam having a proximal end and a distal end; acutoff blade rotatably connected to said distal end; and drive means fordriving the rotation said cutoff blade, said drive means connected tosaid proximal end of said support beam.
 9. The cutoff saw assembly asdescribed in claim 8 wherein the drive means comprises a drive motorconnected said proximal end of said support beam.
 10. A method forremoving excess material from a casting comprising the steps of: a)engaging the casting with a robot arm; b) transporting the casting to aposition proximate a cutoff blade; c) controlling the force of saidcutoff blade with a compliance control system; and d) urging the castinginto said cutoff blade with said robot arm.
 11. The method for removingexcess material from the casting as described in claim 10, wherein priorto step a) including the step of: programming a system controller tocooperatively manage said robot arm and said compliance system forremoving the excess material from the casting.
 12. The method asdescribed in claim 10 wherein step c) further comprises the steps of:positioning an actuator between said cutoff blade and a frame;connecting said actuator to a compliance regulator; connecting saidcompliance regulator to a system controller; and controlling thepressure in said actuator with said compliance regulator.
 13. Acompliance cutoff saw assembly for removing excess material from acasting comprising: a robot to engage the casting; a frame positionedopposite said robot; a blade attached to said frame; and compliancemeans mounted between said blade and said frame for supporting saidblade with an adjustable force; wherein said robot transports thecasting into said blade to remove the excess material.
 14. Thecompliance cutoff saw assembly as described in claim 13 furthercomprising a system controller connected to said compliance means andconnected to said robot; said system controller regulating theconcurrent operation of said robot and said compliance means.
 15. Thecompliance cutoff saw assembly as described in claim 14 wherein saidcompliance means comprises: a compliance actuator; and a complianceregulator connected between said compliance actuator and said systemcontroller; wherein said compliance regulator controls the force exertedby said compliance actuator according to said system controller.
 16. Thecompliance cutoff saw assembly as described in claim 15 wherein saidcompliance actuator is a pneumatic actuator.
 17. The compliance cutoffsaw assembly as described in claim 16 wherein said compliance actuatoris a hydraulic actuator.
 18. The compliance cutoff saw assembly asdescribed in claim 15 wherein said frame includes: a mounting assemblyhaving a shaft and a pair of bearings; and a support beam pivotallymounted to said mounting assembly, said support beam having a distal endand a proximal end; wherein said blade is connected to said distal endof said support beam.
 19. The compliance cutoff saw assembly asdescribed in claim 18 wherein said blade is rotatably mounted to saiddistal end of said support beam, and wherein said assembly furthercomprises drive means for rotating said blade.
 20. The compliance cutoffsaw assembly as described in claim 13 wherein said robot comprises: amulti-positional robot arm; and a tooling clamp attached to said roboticarm to engage the casting.